WOODBURY COUNTY, Iowa (NEXSTAR/KCAU) – Hundreds of migrating waterfowl were hit and killed Monday night after a weather phenomenon in northwest Iowa apparently caused them to mistake wet parking lots and roads for wetlands and marshes.

State conservation officer Steve Griebel, of Woodbury County, said in a release that phone calls and text messages about the birds started coming in around 9:30 p.m. Monday. He said he received more early Tuesday morning.

“I counted over 200 dead ducks on the highway, and can only imagine how many dead ones were out of sight in the ditch,” Griebel said after seeing it firsthand Wednesday while driving on Highway 20. “It was all different species, mostly bluebills, but there were mallards, buffleheads, teal. It must have been an epic migration.”

The migration began as ducks and geese headed south once bitter cold settled into central Canada and the Dakotas. A strong mixed-precipitation weather front forced the waterfowl to set down.

“Situations similar to this one has been known to occur when you have extreme cold weather that collides with a strong front,” Orrin Jones, state waterfowl biologist for the Iowa Department of Natural Resources, said in a release. “This is a unique, one-time event that there’s nothing much we could do about, and should be over now.”

The DNR said people seeking to use the road-killed ducks will need to provide a valid hunting license, habitat fee, migratory game bird fee and federal duck stamp. They must also follow daily bag and possession limits.

Unique weather in the Upper Midwest appears to be common in November. The most famous was on Armistice Day in 1940, when it went from temperatures in the mid-50s to more than a foot of snow, resulting in 150 people and thousands of livestock dead.